18 August 2014

Jane McCredie: Genetic scapegoats

“LOOK at beautiful pictures, study perfect pieces of statuary, forbid as far as possible the contemplation of unsightly and imperfect models”, was the advice Mrs Emma Drake MD gave to pregnant women in her 1908 instructional manual, What a Young Wife Ought to Know.

Medical experts of the time believed the sights and experiences a woman was exposed to during pregnancy would help determine the health, even the physical appearance, of her unborn child.

Nineteenth-century Parisian surgeon Jean Samuel Pozzi, for example, declared “the influence of strong emotions [during pregnancy] on the production of monstrosities seems established by very strong proofs”, while Mrs Drake noted the striking resemblance of Italian infants to baby Jesus, apparently a result of the hours their mothers had spent contemplating images of the Madonna.

Such ideas might seem laughable to us now, but the burgeoning science of epigenetics is making us look again at how a woman’s experiences before and during pregnancy might affect fetal development and the future health of her baby.

Epigenetic changes, which may be triggered by environmental factors such as chemical exposure or diet, don’t alter our overall genetic make-up but they can lead to particular genes being switched on or off (or being up- or down-regulated).

That, in turn, may affect health outcomes, making us more susceptible to particular diseases, for example.

Our growing understanding of these potentially modifiable epigenetic effects could open up new pathways for prevention, but does it also raise a renewed risk of stigmatising women whose children experience health problems, in the same way their 19th century forebears were held responsible for the birth of a child with disabilities?

A group of US researchers — including scholars in public health, history of science, anthropology and philosophy — is arguing we need to ensure the potential health benefits of epigenetic research do not come at the cost of constraining women’s freedom.

“There is a long history of society blaming mothers for the ill health of their children”, the group writes in Nature, warning that “exaggerations and over-simplifications [of epigenetic research] are making scapegoats of mothers, and could even increase surveillance and regulation of pregnant women”.

They believe there’s a precedent. Punitive measures, even criminal sanctions, have been imposed in recent decades on women consuming alcohol or illegal drugs during pregnancy, in some cases on the basis of pretty sketchy evidence.

So what are we to make of epigenetic studies suggesting a link between poor maternal diet, say, and a child’s future risk of obesity, diabetes and other adverse health outcomes?

These authors argue the discussion often focuses too narrowly on the behaviour of the pregnant woman, ignoring other potential factors such as socioeconomic status or the health behaviours of the father (a child’s health may also be affected by epigenetic changes in sperm, triggered by smoking and other factors).

When a 2012 study found an increased mammary cancer risk in daughters and granddaughters of pregnant rats fed a high-fat diet, it prompted media headlines such as “Why you should worry about grandma’s eating habits” and “Think twice about that bag of potato chips because you are eating for more than two”.

As the group of researchers point out in their Nature article, the reports did not acknowledge the rats had been specially bred for high cancer rates and glossed over inconsistent results (the third generation offspring of those on the high-fat diet actually had lower cancer rates than controls, for example).

Media reports of such studies also often fail to acknowledge that findings in animals will not necessarily translate into humans.

Epigenetic research is offering extraordinary insights into the origins of disease, but it’s never going to hold all the answers. In fact, if it leads to an over-simplified focus on blaming mothers, it could even become part of the problem.

When the aim is improved child health, the chemical markers placed on our genes are part of the picture, but they need to be seen in the context of the myriad social factors affecting the health and functioning of children and their parents, mothers and fathers.

Jane McCredie is a Sydney-based science and medicine writer.

Poll

Are punitive measures, such as criminal sanctions, justified for pregnant women whose lifestyle behaviours could affect the fetus?

4 thoughts on “Jane McCredie: Genetic scapegoats”

This piece was not really about epigenetics. It was about known risk factors for foetal health. They were known before the word “epigenetic” existed, I think. So why conflate the mechanism (epigentetics) with the cause (poor health behavoiors and social class)?

As for blaming the mother, well if the mother is going to smoke during pregnancy, she is going to be blamed, and rightfully so. Even if 25% of women who smoke smoke during pregnancy. I am sure that much less than 25% of smoking women don’t care about their children, so it just goes to show how addictive smoking is.

As an aside, apparently herpes simplex 2 and toxoplasmosis infection in mothers is associated with increased risk of schizophrenia in her offspring. Run that up the flag pole and see how many people salute it.

As a mere student, I continue to be both shocked and irritated (disgusted?) by the misconceptions (ignorance?) of health professionals about genetics, but particularly the misunderstandings about epigenetics.

It should be mandatory for GPs AND specialists to have a solid understanding of genetics. If they attended Uni before the mapping of the genome in 2003, their genetics knowledge is most likely insufficient! (My geneticist friend was unable to return to her research position after a 10-year absence given the profound advances in knowledge over the past decade.)

Evidence based medicine demands a a thorough understanding of genetics. We need to be able to treat patients more as individuals and start seeing population-based approaches for what they are: treating everyone as an average while ignoring the possibility of tail dwellers/outliers. Who is more likely to be seeking medical help for conditions that are NOT attributable to smoking, alcohol consumption, overeating or a sedentary lifestyle?!

We must overcome an apparent fear of reality and stop obsessing over social factors given twin studies and the clear evidence that only very acute/ hronic abuse and deprivation trigger health problems while heritable factors underlie just about every health condition. Even injury is more likely in those who suffer heritable self-regulatory deficits or increased impulsivity.

Our aim should be to help patients achieve the best health status possible. Enormous leaps forward in cancer interventions are largely attributable to molecular biology and genetics. We need to keep learning and enjoy it. Otherwise, leave the medical profession.

Mere student Elisabeth seems upset about something. Old doctors without a handle on genetics? Over-emphasising modifiable risk factors over non-modifiable ones? Society’s complusion to blame something/someone else for how things are in the world?

Our mutational burden is increasing. The inevitable outcome will be extinction for all species. Does that mean we shouldn’t do what we can to improve what we can? It would be very nice to individualise treatment according to a paticular patient’s genetics but we don’t have the technology at the front lines yet.

And evidence-based medicine is not as pure as we might hope. The evidence may not even have been gathered, and when it is, it has to be interpreted by humans, each with their own bias. Just because most people believe it doesn’t mean it is actually right.

The term ”epigenetics” is indeed not well understood by many, and is already being misapplied by the pseudo-scientists to push particular ideologies. For example, the more radical end of the natural childbirth movement is trying to argue that cesarean birth – ie the machanical route by which a child is born, lasting between minutes to hours, might affect gene expression. To people with an understanding of the clinical sciences, this does not sound plausible.

I would remind Elisabeth that we were all students once, full of knowledge but lacking the reality of practice. We have to apply what is known, and make individualised decisions (together with patients) eveery day, and be held to account for the way we do it. One’s shock/irritation/disgust tends to recede in the face of the realities of practice. And, thankfully, access to good information is more accessible than ever before.